Anti-war protesters managed to break into Prestwick Airport and board a US Air Force aircraft despite a step up in security after a breach the previous day, a court was told yesterday.

Marcus Armstrong, 47, from Milton Keynes, one of three members of the Trident Ploughshares protest group who are accused of breaking into the airport and boarding a C130 military plane, was allegedly apprehended in the cockpit.

At Ayr Sheriff Court yesterday Constable Craig Beaver, 28, one of two arresting officers, was convinced only two were arrested on the plane and was unable to identify the faces of those who had been detained as they sat in the dock. They included Mr Armstrong, who he had allegedly arrested.

He also admitted that people on the plane in camouflage uniform, who said they were aircraft personnel with the "US Army or Air Force", had not been asked for identification.

Mr Armstrong; Christopher Bluemel, 26, of Southampton; and Angela Zelter, 56, of East Runton, Norfolk, all appeared before Sheriff John Montgomery charged with entering the restricted zone and getting into the military craft without permission in the early hours of August 7, 2006.

A further four airport activists were arrested after allegedly getting into a controlled area of the airport having broken through a 2.7 metre-high security fence, the court heard. Sarah Lazenby, 69, of Oxford; Jean Oliver, 47, and Douglas Shaw, 58, from Biggar in South Lanarkshire; and Matthew Bury, 52, of Somerset, are accused of entering without lawful authority or reasonable excuse.

Olivia Agate, 66, of Menston, near Leeds, is charged with aiding and abetting four protesters by driving them to the airport.

The incident was the second of three security breaches at the airport by Trident Ploughshares that resulted in arrests.

Airport operations director Steve Thomson, 44, said security was stepped up after the breach a day earlier. "There were additional security patrols on the boundary during the dark hours," he said.

PC Beaver and PC Barry Gibson, 29, boarded the military aircraft to make the arrests. PC Beaver said one of the protesters was in the cockpit and another was at the rear of the aircraft. They had been wearing outdoor clothing, thick jackets and back packs.

"I informed the man in the cockpit that he was under arrest," said PC Beaver. "It was under the Aviation Security Act, for being in an airfield while unauthorised."

He admitted he could not recognise the intruder's face if he saw him again and could not identify him or the other male intruder from the seven in the dock.

He said both intruders on the plane were handcuffed and were led off the aircraft and that two people, rather than three, were detained for questioning.

Earlier, PC Gibson said there were two men and one female arrested on the C130.

The trial continues.